1. Field of the Invention
Embodiments of the present invention relate to improvements in caster centering devices. Primarily devices for use in airplane landing gear to bring the nose wheel of the landing gear into parallelism with the fuselage of the plane, so that upon landing the caster wheel will be disposed in alignment with the direction of flight and upon retraction the landing gear is in alignment with the storage compartment.
2. Relevant Background
Aircraft landing gear, attached to primary structural members of the aircraft, support the entire weight of an aircraft during landing and ground operations. Most landing gear includes wheels to facilitate operation to and from hard surfaces, such as airport runways.
Numerous configurations of landing gear types can be found. Three basic arrangements of landing gear include: tail wheel-type landing gear, tandem landing gear, and tricycle-type landing gear. Tail wheel-type landing gear is generally comprised of a main gear assembly located forward of the center of gravity and an additional wheel assembly to support the tail. Alternatively, tandem landing gear has the main gear and tail gear aligned in the longitudinal axis of the aircraft. Sailplanes and certain large aircraft employ such a tandem configuration. In contrast, tricycle-type landing gear includes a main gear assembly and a nose gear.
The nose gear of some aircraft with tricycle-type landing gear is steerable from the flight deck via a nose wheel steering system. Conversely, other aircraft include nose wheel assemblies that caster (swivel freely in a horizontal plane). Such aircraft are steered during taxi by differential braking and use aerodynamic control surfaces during takeoff and landing to maintain directional control.
A further classification of aircraft landing gear can be made into two categories: fixed and retractable. Many small, single engine light aircraft have fixed landing gear, which means the gear is attached to the airframe and remains exposed to the slipstream as the aircraft is flown. However, as the speed of an aircraft increases, the drag caused by the fixed landing gear (parasite drag) also increases. To minimize parasite drag, mechanisms to retract and stow the landing gear are often employed. While in flight, retractable landing gear stows in the fuselage or wing compartment wheel wells. Once in these wheel wells, the landing gear is out of the slipstream and does not create any parasite drag.
Another category of aircraft that employ retractable landing gear is amphibians. Amphibious aircraft possess the ability to land and takeoff from the water as well as from land based runways. While the fundamentals of landing gear retraction and extension remain the same, the process must also consider the hydrodynamic forces and that the gear may be submerged for extended periods of time.
Presently, retractable aircraft landing gear that include a castering wheel assembly are susceptible to incorrect wheel orientation upon retraction assembly into the fuselage or wing storage compartment. If retracted in an improper position, the castering wheel assembly may not fit into the intended storage compartment and, consequently, doors to the landing gear storage compartment cannot close. Such a scenario can result in numerous problems, including breaking of one or more doors, stalling of one or more actuators, etc. And in the case of an amphibious aircraft an improperly retracted landing gear may result in unacceptable hydrodynamic performance that may jeopardize the ability to become safely airborne or safely land on water.
In light aircraft, especially Light Sport Aircraft or light amphibious aircraft, weight and complexity are driving design considerations. While landing gear centering mechanisms exist in the prior art they are, in many instances provide at the cost of increased weight and complexity. The challenge is therefore to produce a landing gear centering mechanism that is effective in orienting the landing gear prior to retraction and after extension and that is simple and minimizes financial and weight costs.
These and other challenges of the prior art are addressed by one or more embodiments of the present invention. That is to say, the present invention provides a simplified aircraft landing gear that self-orients and thus properly orients itself for storage within a storage compartment.
Additional advantages and novel features of this invention shall be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following specification or may be learned by the practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities, combinations, compositions, and methods particularly pointed out in the appended claims.